Stenciling process



y 8, 3 c. 1.. MARTIN; 1,957,660

STENCILING PROCESS Filed Feb. 29. .1932

F 1;; 1 F19. E 0-73 9 [3 A5 L K 2/ Inuanlur Carl I... iF'lTfi Patented May 8, 1934 STENCILING PROCESS Carl L. Martin, Chicago, Ill., as'signor, by mesne assignments, to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application February 29, 1932, Serial No. 595,682

Claims.

The present invention relates in general -to stenciling processes, but is particularly concerned with a stenciling process which enables the fast and very accurate stenciling of small parts.

5 The essential equipment for carrying out applicants process of stenciling designations on small faceplates suitable for use on a power supervisor's board, such as illustrated in White application, Serial'No. 425,121, filed February '1,

1930, has been shown inthe accompanying drawing, in which- Figs. 1 and 3 are plan, and perspective-sectional views, respectively, of the stenciling screen employed; Figs. 2 and 4 are plan and sectional .5 views, respectively, of a magnetic chuck; Fig. 5 is a perspective view of a squeegee; Figs. 6 and 7 are perspective views of face-plate units before and after stenciling, respectively; while Fig. 8 illustrates a form of tool suitable for removing the face-plates from the chuck.

The screen employed, as shown in Figs. 1 and 3, comprises aframe portion 11 having secured thereto a screen portion 12. The screen portion comprises fine gauge silk tightly stretched over the frame. This silk is covered with a sheet of celluloid from which have been cut the designations to be stenciled. In the illustration the same designation has been repeated three times to enable three face-plates to be stenciled at a time. By use of a solvent of the celluloid, the sheet thereof is glued, so to speak, to the silk, thus making the screen impenetrable, excepting where the stencils appear therein. Appropriate alignment pins 13 and 14 in the frame of the screen are arranged to register with the holes 13' and 14 in the chuck, so as to properly position the frame with respect to the chuck.

The chuck employed comprises an iron face portion 24 which has, in the present illustration, three cut-out portions 15 for receiving three of the face-plates to be stenciled. Associated with each of these cut-out portions is a magnet 19 having a core 17 extending through the portion 15 flush with the bottom of the cut-out portion. The core 17 is surrounded by a nonmagnetic sleeve 18 so that the pull of the magnet 19 will be concentrated at the cut-out portion and will serve to securely hold the faceplate in place when the magnet is energized. The magnet 19 and the magnets of the other cut-out portions are ordinarily connected in the same circuit and are energized upon operation of a foot switch 20. The cut-out portions 16 in plate 24 enable a tool, such as illustrated in Fig. 8, to be inserted beneath the stenciled faceplates, to assist in their removal from the chuck. The squeegee, Fig. 5, comprises a handle portion 21 and a rubber portion 22 and is substan-' tially the same width as is the inside of the. frame 11. In carrying out the stenciling process, .blank' face-plates, such as shown in Fig. 6, are first; placed in the chuck. An appropriate screen, such as the one shown in Figs. 1 and 4, is placed over the chuck. A quantity of the paint to be employed is then placed on the upper portion of the screen surface and the squeegee drawn over the length of the screen. ,By this action paint will be forced through the stenciled portions of the screen into contact withthe elements being stenciled. The foot switch 20 is now operated to energize the magnets, such as 19, to hold the stenciled face-plate elements in the chuck, while the screen is withdrawn therefrom. The foot switch is now released, after which the stenciled elements are readily removed with the assistance of a tool, such as the one shown in Fig. 8.

. In stenciling a large number of elements the foregoing process is simply repeated, aquantity ofpaint being placed upon the screen from time to time as required.

What is claimed is:

1. The process of accurately applying designations to small parts, consisting of the placing of such parts in a fixture; placing a screen over the the fixture in a definite predetermined relation thereto; placing a quantity of a stenciling compound on one end of the screen, drawing a squeegee over the screen and thereby forcing a portion of the compound into the mesh of the unsealed or stencil portions of the screen and against the parts to receive the designations, of holding such parts 'against the lifting tendency of the screen as the screen is lifted clear of the fixture, of disabling the holding of such parts and then lifting them clear of the fixture. 2. The process of accurately applying designations to small parts, consisting of the placing of such parts in a fixture; placing a screen over the fixture in a definite relation thereto; placing a quantity of a stenciling compound on one end of the screen, drawing a squeegee over the screen and thereby forcing a portion of the compound into the mesh of the unsealed or stencil portions of the screen and against the parts to receive the designations, and of magnetically holding such parts against the lifting tendency of the screen only as the screen is lifted clear of the parts and fixture.

8. The process of accurately applying designathe screen,

tions to small parts of magnetic material, consisting of placing such parts in a chuck, placing a stenciling screen over the chuck in a definite relation thereto, placing a stenciling compound upon forcing the compound through the screen against the parts, magnetically holding the parts in the chuck while the screen is lifted therefrom, discontinuing the magnetic holding of the parts in the chuck and then removing the parts;

4. The process of accurately applying designations to small parts of magnetic material, consisting of placing such parts in a. chuck, placing a stenciling screen over the chuck in definite relation thereto, placing a stenciling compound upon the screen, forcing screen against the-parts, then magnetically-holding the parts in the chuck while the screen is the compound through the lifted therefrom, and then discontinuing the magnetic holding of and removing the parts, the foregoing operations, excluding the placing of more compound on the screen, being repeated each time new parts are placed in the chuck and the compound being added only from time to 

